This invention relates to an attachment for loading and unloading a constructional material, and more particularly to an attachment adapted to be mounted in a manner similar to a bucket on an arm of a vehicle having a hydraulic shovel used for construction work to load and unload a constructional material such as a concrete block, a U-shaped drainage conduit, a Hume pipe or the like.
Conventionally, work such as the arrangement and storage of the constructional material described above in a manufacturing factory, a construction site or a work site; the loading and unloading of the constructional material with respect to a truck; the heaping-up of the constructional material in a work site, or the like is generally manually carried out. This a because the weight of the constructional material is small to an extent that it can be manually transported, and a construction or work site generally fails to provide a work area sufficient to make mechanization of the work possible. However, the handling of the constructional materials which can be as many as ten to a hundred times a day not only is physically cruel but requires much time and labor, resulting in working efficiency being substantially deteriorated. Thus, labor saving and an improvement in working efficiency have been highly desirable.
Also, an attachment to a hydraulic shovel which has been conventionally used to load and unload a constructional material such as a concrete block is generally constructed in a manner like a fork claw. Unfortunately, the attachment a large force produced by a hydraulic cylinder of an arm of the hydraulic shovel to be transmitted directly to the constructional material through the attachment, resulting in the constructional material interposedly held by the attachment being broken or damaged, so that use of the attachment is substantially limited.